Apparatus and method for transmitting variable rate data according to multiple storage state indicators

ABSTRACT

DVD reproducing apparatus which transmits variable-bit rate data on a digital serial bus having a predetermined transmission rate. The apparatus employs a reproducing device to reproduce data from a record medium in accordance with a control signal to produce variable rate data. The control signal is generated on the basis of at least two buffer storage state indicators corresponding to respective data buffers, one of which is incorporated into the reproducing device. The peak data rate of the variable rate data is detected, a rate of transmission of the variable rate data is established in accordance with the detected peak data rate, and the variable rate data is transmitted in accordance with the established transmission rate.

BACKGROUND OF THE INVENTION

The present invention relates to apparatus and method for transmittingdata and, more particularly, to apparatus and method for transmittingvariable-bit rate data on a digital serial bus having a predeterminedtransmission rate. The invention also relates to apparatus and methodfor transmitting variable-bit rate data on a digital serial bus withmeans for pre-determining the peak bit rate of the variable-bit rate tobe transmitted.

As is known, various types of digital video-audio equipment, forexample, DVD reproducing devices, digital VTRs, digital televisions,etc., are currently available for consumer use. Several such devicesreproduce or receive digital video/audio signals, convert those signalsinto analog signals, and supply the analog signals to analog-typevideo/audio equipment. It is also generally desirable to supply fromsuch equipment digital video/audio signals to, for example, a personalcomputer, a digital television receiver, or other type of digitaldevice.

The communication system IEEE-1394 is a digital serial bus which hasbeen proposed as a means for transmitting such digital video/audiosignals between digital devices. Referring to FIG. 1 of the drawings, anexemplary block diagram of an IEEE-1394 system that includes anIEEE-1394 bus 901 and various digital devices 902-907 is shown. In theexemplary block diagram, the IEEE-1394 bus is coupled between a DVDreproducing apparatus 902, a digital VCR 903, a digital broadcastingreceiver 904, a digital television receiver 905, a digital televisionreceiver 906 and a personal computer 907. As shown, digital video/audiodata is supplied from DVD reproducing apparatus 902 via the IEEE-1394bus to digital television receiver 906, and digital video/audio datasupplied from digital broadcasting 904 is supplied via bus 901 todigital television receiver 905. Given an IEEE-1394 bus with atransmission rate of, for example, 100 Mbps, and video/audio data isorganized into "units" of data, then in accordance with IEEE-1394standard, 4915 units of data can be transmitted during each 125 μsectransmission cycle of the bus. In accordance with this standard, thenumber of units transmitted corresponds to the bit rate of the signal tobe transmitted. For example, to realize a communication speed ofapproximately 10 Mbps, which corresponds to the mean bit rate of atypical video signal, then approximately 1200 units are needed. However,to realize a communication speed of approximately 2 Mbps, which is themean bit rate of an audio signal, then approximately 704 units areneeded.

One limitation of the above discussed IEEE-1394 standard is that signalsare transmitted only after their transmission rate (i.e., bit rate) isdetermined. However, DVD reproducing devices that employ MPEGencoders/decoders reproduce digital video/audio data at a variable rateand, thus, an IEEE 1394-bus previously has been unable to transmitvariable rate data reproduced from such devices.

OBJECTS OF THE INVENTION

Therefore, it is an object of the present invention to provide apparatusand method for transmitting digital video/audio data which overcome theshortcomings of the above described system.

Another object of the present invention is to provide apparatus andmethod which is operable to transmit variable rate digital video/audiodata in accordance with the IEEE-1394 standard.

Various other objects, advantages and features of the present inventionwill become readily apparent to those of ordinary skill in the art, andthe novel features will be particularly pointed out in the appendedclaims.

SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, apparatusand method are provided for detecting a peak data rate of variable ratedata to be transmitted, establishing a rate of transmission of thevariable rate data in accordance with the detected peak data rate, andtransmitting in accordance with the established transmission rate thevariable rate data on a transmission line that requires the transmissionrate to be predetermined.

As one aspect of the present invention, a bandwidth of the transmissionline that is required to transmit the variable rate data having thedetected peak data rate is secured.

As another aspect of the present invention, the reproducing of a signalfrom a record medium to produce the variable rate signal is controlledin accordance with a control signal, the variable rate signal isprocessed (e.g., by an MPEG decoder), the control signal is generated inaccordance with a condition of processing of the produced variable ratesignal, and the variable rate signal is transmitted on the transmissionline.

As a feature of this aspect, the transmitted variable rate signal isreceived and processed in a similar manner as that of the producedvariable rate signal (e.g., by a second MPEG decoder), but such secondprocessing does not generate a control signal (similar to the earliergenerated control signal) that represents a condition of the secondprocessing.

As a further aspect of the present invention, the transmitted variablerate signal is received by a receiver (e.g., a digital television), thereceived transmitted variable rate signal is processed, the controlsignal is generated in accordance with a condition of processing of thereceived transmitted variable rate signal, and the generated controlsignal is transmitted back to the transmitting side, wherein thereceived transmitted control signal is utilized to control thereproducing of a signal from the record medium.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description, given by way of example and notintended to limit the present invention solely thereto, will best beappreciated in conjunction with the accompanying drawings, wherein likereference numerals denote like elements and parts, in which:

FIG. 1 is a block diagram of a system employing an IEEE-1394 digitalserial bus;

FIG. 2 is a block diagram of a data transmission apparatus in accordancewith the present invention;

FIG. 3 is a block diagram of a data transmission apparatus in accordancewith another embodiment of the present invention;

FIG. 4 is a simplified block diagram of the device shown in FIG. 2;

FIG. 5 is a simplified block diagram of the device shown in FIG. 3;

FIG. 6 is a block diagram of control circuits 301 and 302 in accordancewith the present invention;

FIG. 7 schematically illustrates the data structure of an Iso packet;and

FIG. 8 is a schematic illustration of the transmission bandwidth of adigital serial bus that is transmitting data in accordance with thepresent invention.

DETAILED DESCRIPTION OF CERTAIN PREFERRED EMBODIMENTS

FIGS. 2 and 3 illustrate different embodiments of the data transmissionapparatus of the present invention, wherein FIG. 2 illustrates a DVDreproducing apparatus 100 that includes an MPEG decoder 6, and FIG. 3illustrates a DVD reproducing apparatus 100 that does not include anMPEG decoder. As will be discussed, DVD reproducing apparatus 100 shownin both FIGS. 2 and 3 are coupled via an IEEE-1394 digital serial bus300 to an MPEG decoder 9, included in, for example, a digital televisionreceiver.

Referring first to the embodiment of the present invention shown in FIG.2, DVD reproducing apparatus 100 is operable to reproduce digitalvideo/audio data from a digital video disk, decode the reproduced datain MPEG decoder 6, and supply the decoded data as respective analogvideo and audio signals. The analog video and audio signals may besupplied to, for example, an analog television receiver, an analogrecording device, etc. DVD reproducing apparatus 100 further is operableto transmit the reproduced digital video/audio data via bus 300 to anexternal MPEG decoder 9 which decodes the transmitted signal andsupplies digital video and audio signals as an output.

DVD reproducing apparatus 100 of the present invention reproducesdigital video/audio data from a digital video disk in a reproducingdevice 1 which supplies the reproduced data via an amplifier circuit 2to a demodulator 3 which demodulates the reproduced signal. Thedemodulated signal is supplied to an error correction and memory controlcircuit 4 which stores the supplied signal in a random access memory 5and corrects errors in the stored signal in a known manner. The errorcorrected signal is supplied to MPEG decoder 6 which includes therein ademultiplexer 61, control circuits 62 and 63, and random access memories64 and 65. The digital signal is supplied to demultiplexer 61 whichdemultiplexes the signal into its respective video and audio components.The video signal is stored via control circuit 62 in memory 64, and theaudio signal is stored via control circuit 63 in memory 65. Controlcircuits 62 and 63 decode the respective stored video and audio signalsin a known manner and the decoded video and audio signals are suppliedas, for example, analog video and audio output signals (after digital toanalog conversion).

In addition to decoding the stored video and audio signals, controlcircuits 62 and 63 supply to a system control circuit 7 respectivecontrol signals that identify the storage states of the respectivememories 64, 65. Similarly, memory control circuit 4 supplies to systemcontrol circuit 7 a control signal that identifies the storage state ofmemory 5. These control signals are sometimes identified as memoryoccupation data and generally identify how much data is stored in therespective memories. System control circuit 7, in response to thesupplied control signals, controls the reproduction of the digitalvideo/audio data by the reproducing device 1 so as to, inter alia,prevent the underflow and/or overflow of the memories.

In accordance with the present invention, DVD reproducing apparatus 100includes a peak rate setting block 8 which sets the peak rate of thereproduced data for purposes of transmission of the variable-rate dataon bus 300 (to be further discussed). DVD reproducing apparatus 100further includes a control circuit 301 which transmits the errorcorrected digital signal output by circuit 4 on bus 300 in accordancewith the IEEE-1394 standard. In addition to supplying the errorcorrected digital video/audio signal to MPEG decoder 6, error correctionand memory control circuit 4 supplies the error corrected digitalvideo/audio signal to peak rate setting block 8.

As previously mentioned, the mean bit rate of a typical video signal is10 Mbps, and the mean bit rate of a typical audio signal is 2 Mbps. Inaccordance with the present invention, peak rate setting block 8 setsthe peak rates of the video and audio signals to twice their respectivemean bit rates, that is, 20 Mbps and 4 Mbps, respectively. Controlcircuit 301 calculates from the supplied set peak rate the number ofunits that are required, and in accordance with the IEEE-1394 standardto provide a total transmission speed of, for example, 100 Mbps on thedigital serial bus, 2400 units and 1408 units are required to transmitthe video and audio signals, respectively. The transmission bandnecessary then is said to be "secured" in accordance with the standard.

Referring to FIG. 8, prior to each 125 μsec transmission cycle of theIEEE-1394 bus 300 during which the video and audio signals aretransmitted, the required transmission band is secured by controlcircuit 301, such transmission band being represented by the dashedrectangular portion in each cycle in FIG. 8. That is, the regionssurrounded by the dashed rectangular portions are said to be "secured"for the data that is to be transmitted by DVD reproducing apparatus 100of the present invention. The hatched portion of each securedrectangular portion of each cycle represents that portion of the securedtransmission band that is actually utilized, i.e., the hatched portionsrepresent the variable rate data itself. The unsecured transmission bandcorresponds to those regions beyond the dashed rectangular portions andare usable by other devices, for example, digital VCR 903 shown in FIG.1.

Control circuit 301 secures the necessary transmission band andsubsequently transmits the digital signal (video and audio) suppliedfrom error correction and memory control circuit 4 on the securedtransmission band of bus 300. The digital signal is transmitted to acontrol circuit 302 which operates to control the bus communication inaccordance with the IEEE-1394 standard, which control circuit 302 beingincluded in, for example, a digital television receiver 200 thatincludes an MPEG decoder 9. Therefore, and in accordance with thepresent invention, variable bit rate data reproduced by DVD reproducingapparatus 100 is transmitted on a digital serial bus in accordance withthe IEEE-1394 standard.

The transmitted video/audio data is supplied from control circuit 302 toMPEG decoder 9 which has a structure similar to that of MPEG decoder 6,but control circuits 92, 93 do not produce control signals that identifythe storage state of memories 94, 95. The digital video/audio signal issupplied to a demultiplexer 91 which demultiplexes the signal into itsrespective video and audio components which are then stored via controlcircuits 92 and 93 in random access memories 94 and 95, respectively.The respective digital and audio signals are decoded by control circuits92 and 93 and the decoded video and audio signals are supplied as, forexample, respective digital video and audio signals.

As previously mentioned, control circuits 92 and 93 do not generatecontrol signals that identify the storage states of memories 94 and 95.DVD reproducing apparatus 100 operates to MPEG decode the reproducedsignal in MPEG decoder 6 and simultaneously transmit the reproducedsignal on bus 300. Since MPEG decoder 9 is equivalent to MPEG decoder 6,and since control circuits 62 and 63 generate respective control signalsrepresenting the storage states of memories 64 and 65, which in turncontrols the reproduction of the data from the digital video disk, it isunnecessary for control circuits 92 and 93 to generate controls signalsthat identify the respective storage states of memories 94 and 95. Inother words, the storage states of memories 64 and 65 should besubstantially equivalent to the storage states of memories 94 and 95,respectively and, thus, proper control of the reproduction of thedigital video/audio data from the digital video disk is provided solelyby MPEG decoder 6.

As previously mentioned, MPEG decoder 6 may supply as outputs respectiveanalog video and audio signals and such signals may be supplied on ananalog signal line 400 to an analog television receiver 500, such asshown in FIG. 4.

In accordance with the present invention, as discussed above, thestorage states of memories 64 and 65 are detected and the reproductionoperation of DVD reproducing apparatus 100 is controlled in accordancewith such storage states thus preventing underflow and overflow ofmemories 64 and 65. By the use of MPEG decoder 6, a separate MPEGdecoder 9, that is coupled to DVD reproducing apparatus 100 of thepresent invention via digital serial bus 300, does not need to determinewhether an underflow or overflow condition of memories 94 and 95 exists.Furthermore, by detecting the peak rate of the supplied digitalvideo/audio signal periodically in peak rate setting block 8, variablerate data may be transmitted on a digital serial bus in accordance withthe IEEE-1394 standard, even when such standard requires that thetransmitted bit rate be known.

Referring next to FIG. 3 of the drawings, a block diagram of apparatusfor transmitting digital video and audio data in accordance with anotherembodiment of the present invention is shown. FIG. 5 also illustratesthe present embodiment, wherein DVD reproducing apparatus 100 is coupledto a digital television 200 including therein a display unit and MPEGdecoder 9. Referring back to FIG. 3, DVD reproducing apparatus 100includes a DVD reproducing device 1, an amplifier 2, a demodulator 3, anerror correction and memory control circuit 4, a random access memory 5,a peak rate setting block 8, a system control circuit 7 and a controlcircuit 301 and thus is similar to DVD reproducing apparatus 100 shownin FIG. 2, except the DVD reproducing device of the present embodimentdoes not include an internal MPEG decoder 6. In the present embodiment,circuits 1-5 operate in a manner identical to that of circuits 1-5 shownin FIG. 2, wherein digital video/audio data is reproduced from a digitalvideo disk, demodulated, stored in memory 5, error corrected in circuit4 and supplied as an error corrected digital video/audio signal tocontrol circuit 301 via peak rate setting block 8. Peak rate settingblock 8 operates in the same manner as that described above with respectto the embodiment shown in FIG. 2 and, therefore, further descriptionthereof is omitted herein. Also, like the embodiment shown in FIG. 2,control circuit 301 shown in FIG. 3 secures the necessary bandwidth inaccordance with the peak rate detected by peak rate setting block 8 andtransmits on bus 300 the error corrected digital video/audio signal inaccordance with the IEEE-1394 standard, all as previously discussed.

The transmitted digital video/audio signal is supplied to a controlcircuit 302 included in digital television receiver 200 which suppliesthe received signal to an MPEG decoder 9 which includes therein ademultiplexer 91, control circuits 92 and 93, and memories 94 and 95.Demultiplexer 91 demultiplexes the transmitted signal into itsrespective video and audio components, and stores the video data viacontrol circuit 92 in memory 94 and stores the audio data via controlcircuit 93 in memory 95. Control circuits 92 and 93 MPEG decode therespective video and audio data to produce respective digital video andaudio signals.

In accordance with the present invention, control circuits 92 and 93detect the storage states (conditions) of memories 94 and 95,respectively (like control circuits 62 and 63 in FIG. 2), and generatetherefrom respective control signals that are supplied to controlcircuit 302. Also in accordance with the present invention, the controlsignals supplied from control circuits 92 and 93 to control circuit 302are transmitted from control circuit 302 on digital serial bus 300 tocontrol circuit 301 in DVD reproducing apparatus 100.

In accordance with the IEEE-1394 standard, control circuits 301 and 302each have a block structure as shown in FIG. 6, wherein each controlcircuit includes an Iso packet transmitting and receiving block 310, abus control block 311, an information signal processing block 312 and aplug control register 313 located within bus control block 311. Isopacket transmitting and receiving block 310 performs isochronouscommunication for transmitting the video signal data and audio signaldata, and bus control block 311 performs asynchronous communication fortransmitting control signals. Data is transmitted between the Iso packettransmitting and receiving block 310 and information signal processingblock 312 within each control circuit 301 and 302. In accordance withthe IEEE-1394 standard, the Iso packet that is transmitted betweencontrol circuit 301 and 302 has the data structure as shown in FIG. 7.

Referring to FIG. 7, each Iso packet is formed from "quadlets" of data,each quadlet consisting of four bytes of information. The Iso packetincludes a header, which includes therein the data length that isprovided in the so-called first quadlet. The Iso packet header furtherincludes in the second quadlet cyclic redundancy check (CRC) codes forthe information of the first quadlet. As shown, the packet header iscomprised of the first and second quadlets, such packet header beingtransmitted at the beginning of packet transmission. A data fieldfollows the packet header, and the cyclic redundancy check codes for thedata field follows that data field.

Bus control block 311 of each control circuit 301 and 302 receives fromthe respective information processing block 312 the control signals thatidentify the storage states of memories 94 and 95. Such information istransmitted from one control circuit to another control circuitutilizing asynchronous communication. Typically, control circuit 302transmits such control signals asynchronously to control circuit 301which subsequently supplies the transmitted control signals to systemcontrol circuit 7. As previously mentioned, bus control block 311 ofeach control circuit 301, 302 includes a respective plug controlregister 313. Plug control register 313 sets values stored therein inaccordance with the transmitted information, for example, thetransmitted signals, and the various information generated by theparticular equipment utilized, and Iso packet transmitting and receivingblock 310 of the respective control circuit 301, 302 is controlled inaccordance with the values stored in plug control register 313.

Finally, the control signals transmitted to system control circuit 7from control 301 operate to control the reproducing operation of DVDreproducing circuit 1 in order to prevent underflow and overflow ofmemories 94 and 95.

Like the first embodiment previously discussed with reference to FIG. 2,the embodiment of FIG. 3 is operable to transmit variable rate dataacross a transmission line, for example, IEEE-1394 bus 300, which has apredetermined rate of transmission. Referring again to FIG. 8, thetransmission band is secured prior to the transmission of the digitalvideo/audio data and, as previously discussed, the hatched portion ofthe secured bandwidth of each cycle represents the variable rate dataitself supplied by DVD reproducing apparatus 100, and the unsecuredtransmission band corresponds to those regions beyond the dashedrectangular portions and are usable by other devices.

While the present invention has been particularly shown and described inconjunction with preferred embodiments thereof, it will be readilyappreciated by those of ordinary skill in the art that various changesmay be made without departing from the spirit and scope of theinvention. For example, the present invention, although described withreference to the IEEE-1394 standard and the use of MPEG decoders, is notlimited to this standard and/or the use of MPEG decoders, but may beapplied to other standards and/or other types of coders/decoders thatproduce/decode variable-rate data.

Therefore, it is intended that the appended claims be interpreted asincluding the embodiments described herein, the alternatives mentionedabove, and all equivalents thereto.

What is claimed is:
 1. Apparatus for transmitting variable rate data ona transmission line requiring a predetermined rate, comprising:means forcontrolling the reproducing of a signal from a record medium by areproducing device to produce variable rate data, said controlling beingperformed according to a control signal generated on the basis of atleast a first buffer storage state indicator corresponding to a firstdata buffer and a second buffer storage state indicator corresponding toa second data buffer, at least one of said first and second data buffersbeing incorporated into said reproducing device; detection means fordetecting a peak data rate of said variable rate data; means forestablishing a transmission rate of said variable rate data inaccordance with the detected peak data rate; and means for transmittingsaid variable rate data on said transmission line in accordance with theestablished transmission rate.
 2. The apparatus of claim 1, wherein saidmeans for establishing includes means for securing a bandwidth of saidtransmission line required to transmit said variable rate data havingsaid detected peak data rate.
 3. The apparatus of claim 2, wherein saidtransmission line has a plurality of cycles, and said means for securinga bandwidth secures the same bandwidth for each cycle of saidtransmission line.
 4. The apparatus of claim 1, furthercomprising:processing means for processing the produced variable ratedata, said processing means including means for generating said controlsignal in accordance with a condition of processing of the producedvariable rate data by said processing means.
 5. The apparatus of claim4, wherein said processing means is operable to MPEG decode the producedvariable rate signal.
 6. The apparatus of claim 4, wherein said secondbuffer is incorporated within said processing means for buffering theproduced variable rate data.
 7. The apparatus of claim 4, furthercomprising reception means for receiving the variable rate datatransmitted on said transmission line, said reception means includingreception processing means for processing the received transmittedvariable rate data in a similar manner as said processing meansprocesses the produced variable rate data, said reception processingmeans not generating a control signal that controls the reproduction ofthe data from the record medium.
 8. The apparatus of claim 7, whereinsaid processing means and said reception processing means are both MPEGdecoders.
 9. The apparatus of claim 1, further comprising:receptionmeans for receiving the variable rate data transmitted on saidtransmission line, said reception means including reception processingmeans for processing the received transmitted variable rate data, saidreception processing means including means for generating varying saidcontrol signal in accordance with a condition of processing of thereceived transmitted variable rate data by said reception processingmeans, said reception means further including reception transmittingmeans for transmitting an indicator of control signal variation to saidtransmitting means; wherein said transmitting means is operable toreceive the transmitted indicator of control signal variation and tosupply the received transmitted indicator of control signal variation tosaid means for controlling.
 10. The apparatus of claim 9, wherein saidsecond buffer is incorporated within said reception processing means forbuffering the received transmitted variable rate data.
 11. The apparatusof claim 10, wherein said reception processing means is an MPEG decoder.12. Apparatus for transmitting variable rate data on a transmission linerequiring a predetermined rate, comprising:a system control circuit forcontrolling the reproducing of a signal from a record medium by areproducing device to produce variable rate data, said controlling beingperformed according to a control signal generated on the basis of atleast a first buffer storage state indicator corresponding to a firstdata buffer and a second buffer storage state indicator corresponding toa second data buffer, at least one of said first and second data buffersbeing incorporated into said reproducing device; a peak bit ratedetector for detecting a peak data rate of said variable rate data; anda bus controller for establishing a transmission rate of said variablerate data in accordance with the detected peak data rate, and fortransmitting said variable rate data on said transmission line inaccordance with the established transmission rate.
 13. The apparatus ofclaim 12, wherein said bus controller is operable to secure a bandwidthof said transmission line required to transmit said variable rate datahaving said detected peak data rate.
 14. The apparatus of claim 13,wherein said transmission line has a plurality of cycles, and said buscontroller secures the same bandwidth for each cycle of saidtransmission line.
 15. The apparatus of claim 12, further comprising:aprocessor for processing the produced variable rate data, said processorbeing operable to generate said control signal in accordance with acondition of processing of the produced variable rate data by saidprocessor; and a transmission line controller for transmitting thevariable rate data on said transmission line.
 16. The apparatus of claim15, wherein said processor is an MPEG decoder.
 17. The apparatus ofclaim 15, wherein said second buffer is incorporated within saidprocessor for buffering the produced variable rate data.
 18. Theapparatus of claim 15, further comprising a receiver for receiving thevariable rate data transmitted on said transmission line, said receiverincluding a reception processor for processing the received transmittedvariable rate data in a similar manner as said processor processes theproduced variable rate data, said reception processor not generating acontrol signal that controls the reproduction of the data from therecord medium.
 19. The apparatus of claim 18, wherein said processor andsaid reception processor are both MPEG decoders.
 20. The apparatus ofclaim 12, further comprising:a transmitter for transmitting the variablerate data on said transmission line; and a receiver for receiving thevariable rate data transmitted on said transmission line, said receiverincluding a reception processor for processing the received transmittedvariable rate data, said reception processor varying said control signalin accordance with a condition of processing of the received transmittedvariable rate data by said reception processor, said receiver furtherbeing operable to transmit an indicator of control signal variation tosaid transmitter; wherein said transmitter is operable to receive thetransmitted indicator of control signal variation and to supply thereceived transmitted indicator of control signal variation to saidreproducing device controller.
 21. The apparatus of claim 20, whereinsaid second buffer is incorporated within said reception processor forbuffering the received transmitted variable rate data.
 22. The apparatusof claim 21, wherein said reception processor is an MPEG decoder. 23.Method of transmitting variable rate data on a transmission linerequiring a predetermined rate, comprising the steps of:controlling thereproducing of a signal from a record medium by a reproducing device toproduce variable rate data said controlling being performed according toa control signal generated on the basis of at least a first bufferstorage state indicator corresponding to a first data buffer and asecond buffer storage state indicator corresponding to a second databuffer, at least one of said first and second data buffers beingincorporated into said reproducing device: detecting a peak data rate ofsaid variable rate data; establishing a transmission rate of saidvariable rate data in accordance with the detected peak data rate; andtransmitting said variable rate data on said transmission line inaccordance with the established transmission rate.
 24. The method ofclaim 23, wherein said step of establishing is carried out by securing abandwidth of said transmission line required to transmit said variablerate data having said detected peak data rate.
 25. The method of claim24, wherein said transmission line has a plurality of cycles, and thesame bandwidth is secured for each cycle of said transmission line. 26.The method of claim 23, further comprising the steps of:processing theproduced variable rate data; generating said control signal inaccordance with a condition of processing of the produced variable ratedata; and transmitting the variable rate data on said transmission line.27. The method of claim 26, wherein said processing step is carried outby MPEG decoding the produced variable rate signal.
 28. The method ofclaim 26, wherein said processing step includes the step of bufferingthe produced variable rate signal said second buffer.
 29. The method ofclaim 26, further comprising the steps of receiving the variable ratedata transmitted on said transmission line, and processing the receivedtransmitted variable rate data in a similar manner as said variable ratedata is processed in said first processing step, wherein a controlsignal representing a condition of processing of the receivedtransmitted variable rate data similar to the previously generatedcontrol signal is not generated.
 30. The method of claim 29, whereinsaid first and second processing steps are carried by respective MPEGdecoders.
 31. The method of claim 23, further comprising the stepsof:transmitting from a transmission side the variable rate data on saidtransmission line; receiving the variable rate data transmitted on saidtransmission line; processing the received transmitted variable ratedata; varying said control signal in accordance with a condition ofprocessing of the received transmitted variable rate data; transmittingan indicator of control signal variation on said transmission line; andreceiving at said transmission side the transmitted indicator of controlsignal variation; wherein the received transmitted indicator of controlsignal variation is utilized to control the reproducing by saidcontrolling step.
 32. The method of claim 31, wherein said processingstep includes the step of buffering the received transmitted variablerate data in said second buffer.
 33. The method of claim 32, whereinsaid processing step is carried out by an MPEG decoder.
 34. Apparatusfor transmitting variable rate data on a transmission line requiring apredetermined rate, comprising:a system control circuit for controllingthe reproducing of a signal from a record medium by a reproducing deviceto produce variable rate data, said controlling being performedaccording to a control signal generated on the basis of at least a firstbuffer storage state indicator corresponding to a first data buffer anda second buffer storage state indicator corresponding to a second databuffer, at least one of said first and second data buffers beingincorporated into said reproducing device; a detecting circuit; atransmission rate circuit coupled to the detecting circuit; and atransmitting circuit coupled to the transmission rate circuit; whereinthe detecting circuit detects a peak data rate of said variable ratedata; wherein the transmission rate circuit establishes a transmissionrate of said variable rate data in accordance with the detected peakdata rate; and wherein the transmitting circuit transmits said variablerate data on said transmission line in accordance with the establishedtransmission rate.
 35. The apparatus of claim 34, wherein saidtransmission rate circuit includes a bandwidth circuit which secures abandwidth of said transmission line required to transmit said variablerate data having said detected peak data rate.
 36. The apparatus ofclaim 35, wherein said transmission line has a plurality of cycles, andsaid bandwidth circuit secures the same bandwidth for each cycle of saidtransmission line.
 37. The apparatus of claim 34, further comprising aprocessing circuit, for processing the produced variable rate datawherein said processing circuit includes a generating circuit whichgenerates said control signal in accordance with a condition ofprocessing of the produced variable rate data by said processingcircuit.
 38. The apparatus of claim 37, wherein said processing circuitis operable to MPEG decode the produced variable rate signal.
 39. Theapparatus of claim 37, wherein said second buffer is incorporated withinsaid processing circuit for buffering the produced variable rate data.40. The apparatus of claim 37, further comprising a reception circuitwhich receives the variable rate data transmitted on said transmissionline, said reception circuit includes a reception processing circuitwhich processes the received transmitted variable rate data in a similarmanner as said processing circuit processes the produced variable ratedata, said reception processing circuit not generating a control signalthat controls the reproduction of the data from the record medium. 41.The apparatus of claim 40, wherein said processing circuit and saidreception processing circuit are both MPEG decoders.
 42. The apparatusof claim 34, further comprising a reception circuit for receiving thevariable rate data on said transmission line, wherein said receptioncircuit includes (i) a reception processing circuit which processes thereceived transmitted variable rate data in which said receptionprocessing circuit includes a generating circuit which generates anindicator of control signal variation in accordance with a condition ofprocessing of the received transmitted variable rate data by saidreception processing circuit and (ii) a reception transmitting circuitwhich transmits the generated indicator of control signal variation tosaid transmitting circuit, and wherein said transmitting circuit isoperable to receive the transmitted indicator of control signalvariation and to supply the received transmitted indicator of controlsignal variation to said control circuit.
 43. The apparatus of claim 42,wherein said second buffer is incorporated within said receptionprocessing circuit for buffering the received transmitted variable ratedata.
 44. The apparatus of claim 43, wherein said reception processingcircuit is an MPEG decoder.